Location: Tick and Biting Fly Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Determine if new commercial insecticidal toxicants could be useful as acaricides in the eradication program. Sub-obj. 1.A. Evaluate use of currently available insecticide mixtures that might result in additive or synergistic effects to enhance efficacy in the control of ticks. Sub-obj. 1.B. Evaluate use of long-lasting acaricides for use in regulatory activities of the CFTEP. Sub-obj. 1.C. Evaluate novel methods of acaricide delivery for cattle fever tick control. Objective 2: Develop operationally useful plans for resistance management in fever tick infestations. Sub-obj. 2.A. Evaluate use of Co-Ral for its ability to eradicate organophosphate (OP)-resistant fever ticks in pasture conditions. Sub-obj. 2.B. Characterize emerging resistance to ivermectin and new acaricides in fever tick populations in Mexico. Sub-obj. 2.C. Establish and implement a diagnostic facility to monitor acaricide resistance, define mechanisms of resistance, and provide management strategies for controlling outbreak strains. Objective 3: Develop wildlife-based strategies to eradicate ticks on premises with infested deer, including research on ecology application of anti-tick vaccines and chemicals, novel delivery methods and field trials. Sub-obj. 3.A. Classify habitat preferences of white-tailed deer and cattle fever ticks in Zapata County, TX, using satellite imagery. Sub-obj. 3.B. Analyze genetic associations among populations of southern cattle ticks and cattle ticks, on cattle, white-tailed deer, and other captive and wild ungulates. Sub-obj. 3.C. Evaluate efficacy of ARS-Patented '4-Poster' Deer Treatment Bait Station and medicated baits to eradicate cattle fever ticks feeding on white-tailed deer in infested premises in South Texas. Sub-obj. 3.D. Evaluate efficacy of new acaricides formulated for the '4-Poster' and other topical treatment devices to control blacklegged and lone star ticks feeding on white-tailed deer and cattle fever ticks feeding on deer in infested premises in South Texas. Sub-obj. 3.E. Further develop and field test ARS-Patented Automatic Collaring Device for potential use in applying acaricidal neckbands to control all species of ticks that feed on white-tailed deer. Sub-obj. 3.F. Develop and field test slow-release long-lasting acaricidal neckband formulations for application to deer by the automatic collaring device. Sub-obj. 3.G. Describe relative importance of white-tailed deer as alternative hosts for the dispersal and maintenance of cattle fever tick populations. Objective 4: Perform research to support development of spatial models of adverse economic impact of re-infestation of fever ticks on Texas, other potentially infested states, and the U.S. cattle industry as a whole. Objective 5: Determine risk of Babesia transmission by ticks. Sub-obj. 5.A. Test for presence of Babesia in fever tick outbreak strains in south Texas. Sub-obj. 5.B. Using molecular techniques, evaluate both wild and captive white-tailed deer and exotic ungulates for the presence of Babesia. Sub-obj. 5.C. Determine if Rhipicephalus microplus can acquire Babesia from white-tailed deer and subsequently transmit Babesia to naive cattle.
1b. Approach (from AD-416):
This project addresses the biology and control of ticks of veterinary and human importance with an emphasis on developing technologies to help maintain eradication of cattle fever ticks and the agents that they transmit causing potentially fatal bovine babesiosis and to reduce the risk of humans contracting tick-borne diseases including Lyme disease and human ehrlichiosis. It is a multi-disciplinary project requiring scientists from a wide range of academic specialties, backgrounds, and experiences. The research approach is composed of 5 major objectives including: 1) to evaluate commercially available pesticides for use in the fever tick eradication program, 2) to monitor pesticide resistance in cattle fever ticks and develop plans to mitigate outbreaks of resistant ticks, 3) to develop and evaluate technologies and strategies to eradicate cattle fever ticks or control other tick species feeding on white-tailed deer and other wild ungulates, use satellite image analysis to classify deer habitat preferences, analyze genetic associations among fever ticks and hosts, and to elucidate the relative importance of white-tailed deer as alternative hosts for cattle fever ticks, 4) to continue data input, organization, and development of the GIS database of current and historical fever tick infestation data used to develop descriptive and predictive epidemiological models of fever tick outbreaks, and 5) to determine the risk of Babesia transmission by ticks, including the potential for wild and feral ungulates to serve as reservoir hosts.
3. Progress Report:
Research completed during the fourth year of this project included progress towards developing new tools for host-targeted control of ticks of veterinary/human importance. Testing of 21 outbreak strains of cattle fever ticks for resistance to 5 acaricides found that 5 strains were resistant. These findings were reported to CFTEP officials for use in planning program treatments in quarantine and outbreak areas. A laboratory strain of ivermectin-resistant fever ticks is being selected with ivermectin at each generation (current resistance ratio is 8.0). Larvae appear to delay development until ivermectin titers in the host serum drop below a critical threshold, and larvae continue to develop and engorge to repletion 10 days later than what would be expected. Solid feed supplement blocks medicated with ivermectin developed and tested by ARS to eradicate fever ticks on cattle are in the final stages of field testing for use by the CFTEP. This technology has great potential for use as a "stand alone" treatment for eradicating ticks. ARS personnel continue daily input of CFTEP data into GIS databases that are queried to produce imagery to assist CFTEP in designing treatment regimens, evaluating release of temporary quarantines, selection of field sites, visualizing riding trails for tick inspectors, and quantifying ranges of white-tailed deer. In collaboration with scientists at Northern Arizona University, the temporal and spatial genetic relationship of outbreak ticks within and outside the quarantine zone was successfully evaluated. The data revealed low genetic differentiation in a number of tick populations with archived material representing a greater than 2-year time span, suggesting these populations persisted over time despite implementation of eradication protocol. Ticks within and outside the quarantine zone appear to fall within 4 major genetic groups. These findings are the first to evaluate relatedness of outbreak ticks, data that is in support of epidemiological efforts to identify the origin of outbreak ticks and possible dispersal methods. Scientists continued to evaluate attachment and detachment of identification and potentially acaricidal neckbands to wild white-tailed deer with the ARS-patented automatic collaring device. Field evaluations of biological control agents of Arundo donax, an invasive weed that facilitates invasion of fever ticks and reduces visibility/access to the permanent quarantine zone for the CFTEP, were continued. The arundo wasp reached outbreak levels along the Rio Grande, causing significant damage. A second agent, the arundo scale, was established at 9 release sites between Del Rio and Brownsville. Studies of ants at the release sites showed that fire ants can reduce initial establishment of scale if not controlled. Biological studies of a new agent, the arundo leafminer, Lasioptera donacis, and fungi/termites that can decompose dead standing cane were initiated.
1. Pesticide mixtures control pesticide-resistant cattle fever ticks. At the Knipling-Bushland U.S. Livestock Insects Research Laboratory, Kerrville, Texas, the efficacy of pesticide mixtures was evaluated through laboratory and animal experiments to determine if the mixtures were able to better control cattle fever ticks resistant to pesticides. Results of laboratory tests revealed that the pesticide mixtures killed resistant ticks better than when only a single pesticide was used. The highest level of control was obtained with a mixture of two pesticides and another chemical known as a synergist. This mixture yielded >95% control for 28 days post-treatment against cattle fever ticks on live animals under field conditions. This work will potentially aid the U.S. Cattle Fever Tick Eradication program as resistant ticks are common in Mexico and pesticide mixtures are not commonly used in the U.S. to eradicate ticks that cross the boarder from Mexico.
Pound, J.M., Lohmeyer, K.H., Davey, R.B., Miller, J.A., George, J.E. 2012. Efficacy of amitraz-impregnated collars on white-tailed deer (Artiodactyla: Cervidae) in reducing free-living populations of lone star ticks (Acari: Ixodidae). Journal of Economic Entomology. 105(6):2207-2212.